Is It a Poison Ivy Rash? How to Tell—and How to Treat It

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Follow these tips from a dermatologist to ease the itch stat.

Jessica Migala

May 26, 2017

You've probably feared a run-in with poison ivy since you were a kid. Even brushing up against the pointy leaves is risky, says Temitayo A. Ogunleye, MD, assistant professor of dermatology at the Perelman School of Medicine at the University of Pennsylvania. The climbing plant contains an irritating resin, called urushiol, that can transfer to your skin via touch, she explains.

You might also be exposed to the oily liquid by a pet who picks up the resin on his fur and then passes it along to you. You can even inhale urushiol if, say, you mow over a large patch of poison ivy in your yard, Dr. Ogunleye adds. That can cause a severe allergic reaction.

But if only your skin has come into contact with the oil, you'll likely develop an itchy, red, blistering rash within 72 hours. Of course, rashes can be triggered by all sorts of things—including laundry detergent and hair products—but poison ivy rashes tend to be geometric in nature, says Dr. Ogunleye. “Look for a blistering rash in a linear or zigzag pattern,” she says.

How to treat a poison ivy rash

Unfortunately, the rash can last up to three weeks, says Dr. Ogunleye. So part of poison ivy treatment is playing the waiting game until the rash goes away. To ease the itch, apply an over-the-counter hydrocortisone cream. You can also take an OTC oral antihistamine, such as Allegra or Benadryl.

If the rash isn’t starting to get better after a couple of weeks, or it's spreading to other parts of your body, see your primary care physician or a dermatologist. You may need a prescription topical steroid or, in severe cases, an oral steroid, says Dr. Ogunleye.

How to avoid getting poison ivy again

If you know there's poison ivy on your property (the telltale sign is leaves that grow in groups of three) wear gloves when you garden and do other yard work. This isn’t to protect your hands necessarily—the skin on your palms is so thick, urushiol typically doesn’t cause a reaction there. But gloves will help you avoid spreading poison ivy from your hands to other parts of your body.

Also make sure you undress carefully after you do outdoor activities, like hiking and trail running. The resin can stick to your clothes, and transfer to your skin when you take them off. Toss your duds in the wash and hop in the shower ASAP. “The longer the resin stays on your skin, the more likely you’ll have a reaction, and a more intense one at that," says Dr. Ogunleye.